Bus Protection Panel

Definition

• A busbar is one of the power system facilities in the substation, which concentrates and re-distributes electric power by connecting transmission lines and transformer banks. A busbar fault produces a very large fault current, and if clearing is delayed it may spread into a much wider fault. Busbar structures include radial, ring and double busbars; the double busbar is most widely used because it shortens fault duration and offers high reliability and good maintainability. In particular, the 345kV class adopts a 1.5CB structure with three circuit breakers between the two busbars. The 154kV busbar protection panel provides current differential protection for fast and accurate fault detection in a double busbar structure, isolating faults and safely protecting the busbar. Busbar protection is internally divided into separate zone protection (zone 1 or 2) to identify the faulted busbar and overall busbar protection that detects a fault anywhere on the busbar. For example, if both the overall protection and the zone 1 protection detect a fault, the function determines that the fault is on busbar No. 1.

Main functions

• Phase-segregated current differential protection (87B)
• Undervoltage based fault detection (UV/UVS/UVD)
• Overcurrent protection (50BF) for circuit breaker failures
• CT and PT failure detection and alarming
• External fault detection to prevent wrong tripping due to CT saturation
• Busbar-bridged protection according to the status conditions of DS's and alarming for abnormal conditions
• Automated compensation for different CT ratios
• Communication with multiple BUs based on high speed serial communication (1Gbps, fiber optic)
• Fully IEC 61850 compliant, Edition 1
• Self-monitoring on a regular basis

• Current measurement and status monitoring of CB, DS and BFI for two feeders
• Communication with CU based on high speed serial communication (1Gbps, fiber optic)
• Self-monitoring on a regular basis

Specification